Minimum Current Density Research Articles

The effect of various Sn and Ca equal proportional addition on the microstructure, mechanical behavior and corrosion performance of Mg alloys

In the present study, the effects of various Sn and Ca equal proportional addition (0.3:0.1, 0.6:0.2, 1.2:0.4, wt%) on the microstructure, mechanical properties and corrosion behavior of Mg-Sn-Ca alloys were systematically investigated. With the increase of Sn and Ca content, microstructure uniformity of the Mg-Sn-Ca alloy was improved, the average grain size was refined (from 34.4 μm to 21.62 μm, 13.47 μm), and more CaMgSn phases were generated (from 0.39 % to 1.64 %, 4.53 %). With increasing Sn and Ca content, the tensile yield strength (TYS) and ultimate tensile strength (UTS) of Mg-Sn-Ca alloys were gradually increased (TYS: from 91.8 MPa to 98.24 and 125.05 MPa; UTS: from 187.48 MPa to 190.73 and 214.58 MPa), mainly due to the contribution of grain refinement. The electrochemical tests revealed that the corrosion resistance of the Mg-Sn-Ca alloy initially decreases and then increases with the increase of Sn and Ca contents. The hydrogen evolution volume of Mg-0.3Sn-0.1Ca alloy was 41.91 mL cm−2, and the corrosion current density was −1.54 × 10−3 A/cm2. As for Mg-0.6Sn-0.2Ca alloy, deteriorated corrosion resistance compared to the Mg-0.3Sn-0.1Ca alloy was mainly ascribed to the micro-galvanic corrosion between the CaMgSn phase and Mg-matrix. The Mg-1.2Sn-0.4Ca alloy had the best corrosion resistance, with the lowest hydrogen evolution volume of 34.09 mL cm−2 and a minimum current density of −1.15×10−3 mA cm−2, its high corrosion resistance could be attributed to the grain refinement and homogenous distributed CaMgSn phase and more generated Ca(OH)2 product film with dense-structure.

Consequence of coherent Cu5Zr precipitates and Cu2O passive layer formation on the corrosive behaviour of additively processed Cu-Cr-Zr alloy in simulated seawater

Abstract The Cu-Cr-Zr copper alloy is known for its outstanding electrical conductivity and fatigue strength. However, the corrosion behaviour of the copper alloy should also be taken into account when adopting it in industrial applications, especially in the marine environments. This research aims to fabricate Cu alloy coupons using the Laser Powder Bed Fusion (LPBF) technique and subsequently test their corrosive performance in simulated seawater. This research confirms that the Cu5Zr precipitate formation during the LPBF process and the Cu2O passive layer formation were the main reason for the enhanced corrosive behavior of the LPBFed copper alloy. The OM (Optical Microscope), FESEM (Field Emission Scanning Electron Microscope) images supported in evaluating melt pool formations and irregularities, and also confirmed the polycrystalline structure. The diffraction pattern from the TEM (Transmission Electron Microscope) analysis confirmed the formation of Cu5Zr precipitate and grain size distribution, while their orientations were obtained from the EBSD (Electron Based Scattered Diffraction) EBSD analysis. Micro hardness was executed on the scanning and building directions, and it was found that the building direction possessed higher hardness of 54 HV0.3 which was 5% higher than in the scanning direction. This significant fluctuation in the hardness value is due to the closely packed equiaxed and columnar grains along the outer and inner regions of the melt pools. Potentio-dynamic polarization (PD) and electrochemical impedance spectroscopy (EIS) tests were performed on the printed copper alloy parts for various immersion periods of 0, 9, 18 and 38 h. Further, the XRD (x-ray Diffraction) analysis was performed on the corroded surface and it confirmed the Cu2O passive layer and the occurrence of Cu5Zr precipitate. The occurrence of Cu5Zr precipitates and Cu2O passive layer formation helped attain the maximum polarization resistance of 2033.8 ohm and minimum current density of 5.928 × 10−6 A cm−2 with minimum surface roughness of 3.447 μm.

Hot oscillating pressing sintered AlCoCrFeNi/nanodiamond high-entropy alloy composites

AlCoCrFeNi/nanodiamond high-entropy alloy composites were successfully prepared by hot oscillating pressing (HOP) at different sintering temperatures in this work. The microstructures of the HOPed composites consisted of the FCC phase, BCC phase and nanocarbide phase uniformly distributed in the particles interstices. With the temperature increasing, the original powder particle boundaries gradually disappeared, the density progressively increased, and the microstructure defects decreased. At 1100 °C, its maximum density reached to 99.7 %. Moreover, the FCC phase volume fraction and carbide content further increased without significant microstructure coarsening. The hardness and corrosion resistance of the HOPed samples were better than the hot pressing (HP) samples because the original particle boundaries and pores became smaller, and a small number of nanocarbides were uniformly distributed. Then its maximum hardness reached to 566.48 HV1, and the minimum corrosion current density and corrosion rate was 2.916 μm/cm2 and 0.013 mm/year, respectively, which was better than other alloys reported.

Study on the tribological properties and corrosion resistance of the modified NiZnAl-LDH coating on anodic aluminum surface

The porous structure of anodized aluminum creates an opportunity for corrosive media to contact the aluminum substrate, resulting in diminished corrosion resistance and wear performance under adverse conditions. In this study, ternary hydrotalcite containing Ni, Zn, and Al elements, named NiZnAl-LDH, was synthesized on anodized aluminum surfaces using an in-situ growth method. The corrosion and wear resistance of the aluminum substrate were further enhanced by intercalation modification with sodium molybdate. The impact of synthesis parameters, including pH, reaction temperature, and reaction time, on the corrosion and wear resistance of the coating was investigated. Morphology, structure, and properties of the coating were analyzed. The results confirm the synthesis of NiZnAl-LDH modified with sodium molybdate intercalation. Electrochemical tests revealed that immersing NiZnAl-LDH in a sodium molybdate solution with a pH of 9.5 for 2.5 h at 35 °C resulted in a minimum self-corrosion current density of 4.131 × 10−8 A cm−2, significantly enhancing the corrosion resistance of the coating. Friction tests demonstrated a coating friction coefficient of 0.28, indicating excellent tribological performance. The discussed process parameters in this study provide valuable insights for the synthesis and application of LDH, expanding the application of aluminum alloys in the field of corrosion resistance and wear resistance.

Durable slippery liquid-infused porous surfaces for effective corrosion protection of aluminum alloy in ethylene glycol-water solutions

Aluminum (Al) alloys are extensively utilized in liquid-cooling heat dissipation systems owing to their superior strength-to-weight performance, ease of processing, and high thermal conductivity. However, they are susceptible to corrosion in the cooling medium, such as ethylene glycol-water solutions. This study presents a straightforward and cost-effective method to create a slippery liquid-infused porous surface (SLIPS) designed to effectively prevent corrosion of the 6061 Al alloy in ethylene glycol-water solutions. Micro/nano hierarchical structures were achieved on the SLIPS through plasma electrolytic oxidation and hydrothermal treatment. Following the modification of low-surface-energy materials and the infusion of silicone oil, the SLIPS exhibited an outstanding slippery property, allowing ethylene glycol-water droplets to effortlessly slide down the inclined surface at an angle of 1.1°. Additionally, the SLIPS demonstrated remarkable anti-corrosion performance against ethylene glycol-water solutions, with a minimum corrosion current density (Icorr) of 2.4 × 10−10 A·cm−2. Crucially, long-term immersion test results on corrosion resistance revealed that the SLIPS provided reliable corrosion protection for the 6061 Al alloy, exhibiting an Icorr increased by 4 orders of magnitude compared to a smooth substrate. These findings hold significant potential for advancing the widespread application of SLIPS in liquid-cooling heat dissipation systems.

The effect of AlCrN, TiN and Ni-Cr-Nb coatings on the wear and corrosion performance of 45 # steel in 3.5 % sodium chloride solution

The press bar of the oil press is prone to corrosion and abrasion in the high-temperature and high-pressure environment, which reduces the quality of oil and the efficiency of agricultural production. In this paper, Ni-Cr-Nb, TiN and AlCrN coatings were prepared on the surface of press bar substrate by thermal spraying and multi-arc ion plating technology. The tests were analyzed by modern analytical methods such as HV-1000Z micro Vickers hardness tester, SEM, XRD and electrochemical corrosion. The results show that: Vickers hardness tester analysis shows that the surface hardness of AlCrN coating is 3.6 times higher than that of the base material, which is higher than that of several other coatings; SEM shows that the surfaces of the Ni-Cr-Nb, TiN and AlCrN coatings are smooth and even, the film structure is compact and uniform, and the thickness of the coating film is 5.67μm, 6.31 μm and 6.55 μm, respectively; XRD shows the elemental content of each coating, and the Al atoms in the AlCrN coating have good corrosion resistance; Electrochemical corrosion experiment shows that AlCrN coating has the biggest and most important advantages. It shows that AlCrN coating has the maximum potential and minimum corrosion current density, which indicates that its corrosion resistance is the best, followed by TiN coating, Ni-Cr-Nb layer of the corrosion resistance of the first two coatings, but better than the press bar substrate.

Improved mechanical properties and corrosion resistance of Zr-Cu-Al-Ni-Ti bulk metallic glasses by Co addition

Zr-based bulk metallic glasses (BMGs) are considered very promising medical materials because of their high strength and good corrosion resistance. However, poor room temperature plasticity severely hinders their development. In this work, a series of Zr61Cu18Al9Ni7-xTi5Cox (x = 0,1,3,5,7 at.%) BMGs are manufactured using vacuum arc melting technology. The effect of the Co addition on the glass forming ability, mechanical properties, and corrosion resistance is investigated. The results show that the appropriate Co addition can improve the room temperature plasticity and corrosion resistance. Compression tests show that when 1 at.% of Co element is added, the compressive strength is 1769.0 MPa, and the plasticity is 11.5 %, higher than the base alloy Zr61Cu18Al9Ni7Ti5 with 1607.9 MPa and 3.4 %. Corrosion tests show that the passivation interval of all Zr-based BMGs increases with the addition of Co. In particular, the maximum passivation interval of 1.320 V and the minimum self-corrosion current density are exhibited at 5 at.% Co addition. Overall, the effects of Co addition in terms of mechanical and corrosion aspects provide new guidance for the study of Zr-based alloys in the medical field.

Preparation and Performance of Micro-Arc Oxidation Coatings for Corrosion Protection of LaFe11.6Si1.4 Alloy.

The microstructure, corrosion resistance, and phase-transition process of micro-arc oxidation (MAO) coatings prepared on LaFe11.6Si1.4 alloy surfaces in different electrolyte systems were systematically investigated. Research has demonstrated that various electrolyte systems do not alter the main components of the coatings. However, the synergistic action of Na2CO3 and Na2B4O7 more effectively modulated the ionization and chemical reactions of the MAO process and accelerated the formation of α-Al2O3. Moreover, the addition of Na2CO3 and Na2B4O7 improved the micromorphology of the coating, resulting in a uniform coating thickness and good bonding with the LaFe11.6Si1.4 substrate. The dynamic potential polarization analysis was performed in a three-electrode system consisting of a LaFe11.6Si1.4 working electrode, a saturated calomel reference electrode, and a platinum auxiliary electrode. The results showed that the self-corrosion potential of the LaFe11.6Si1.4 alloy without surface treatment was -0.68 V, with a current density of 8.96 × 10-6 A/cm2. In contrast, the presence of a micro-arc electrolytic oxidation coating significantly improved the corrosion resistance of the LaFe11.6Si1.4 substrate, where the minimum corrosion current density was 1.32 × 10-7 A/cm2 and the corrosion potential was -0.50 V. Similarly, after optimizing the MAO electrolyte with Na2CO3 and Na2B4O7, the corrosion resistance of the material further improved. Simultaneously, the effect of the coatings on the order of the phase transition, latent heat, and temperature is negligible. Therefore, micro-arc oxidation technology based on the in situ growth coating of the material surface effectively improves the working life and stability of La(Fe, Si)13 materials in the refrigeration cycle, which is an excellent alternative as a protection technology to promote the practical process of magnetic refrigeration technology.

Correlation between the micro-shot peening coverage and surface microstructural evolution and fluoride-induced corrosion behavior in Monel 400 alloy

This study examines the influence of micro-shot peening (MSP) on Monel 400 alloy, focusing on surface microstructural evolution and fluoride-induced corrosion behavior compared to its solution annealed (SAed) counterpart. MSP treatments were conducted at various surface coverages (100%, 200%, 500%, 1000%, 1500%, and 2000%). Characterization encompassed microhardness, surface roughness, grazing incidence x-ray diffraction (GI-XRD), field emission scanning electron microscopy (FE-SEM) with electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). With increasing the MSP coverage to 2000%, the surface crystallite size decreased from approximately ∼30 µm in the SAed sample to 60 nm. TEM analysis emphasized dislocation slip and formation of dislocation structures as the primary mechanisms for the grain refinement. However, the 2000% coverage exhibited microcrack formation, compromising its hydrofluoric (HF) corrosion resistance. Electrochemical tests revealed severe localized corrosion in all MSP-treated samples except the 1500% coverage, which exhibited a minimum passive current density of 0.2–1.0 µA/cm2. Inductively coupled plasma optical emission spectroscopy (ICP-OES) of immersion solutions showed lower copper and nickel ion concentrations (<150 ppm) in the 1500% MSP-treated sample, indicating its enhanced corrosion resistance. X-ray photoelectron spectroscopy (XPS) identified NiO, NiF2, CuO, CuF2, and Cu(OH)2 phases in SAed and 1500% MSPed samples, with a higher concentration of copper oxide (CuO) in the corrosion film of the 1500% MSP-treated sample, contributing to its superior corrosion resistance.

Techno-economic ionic liquid-based capturing, electrochemical reduction, and hydrogenation of carbon dioxide in the simultaneous production of formic acid and biomethane

CO2 utilization is vital for mitigating climate change by converting CO2 into valuable products, promoting environmental protection and resource efficiency. Novel pathways for CO2 utilization to produce formic acid are proposed namely solute phase electroreduction, gas phase electroreduction, and hydrogenation, are investigated. Employing multi-objective optimization with a deep neural network surrogate model, this study identifies optimal process conditions balancing capital and operational expenditures. The result shows that CO2 hydrogenation ($868 ton−1) exhibits the lowest production cost followed by gas-phase electroreduction ($986 ton−1) and solute-phase electroreduction ($2103 ton−1). The result also shows that without any intervention at all only hydrogenation can generate profit. Furthermore, an in-depth analysis of CO2 emissions indicates that gas phase electroreduction results in the lowest CO2 emissions (0.7 kg CO2 kgHCOOH−1) among the examined pathways. Insights from our research suggest a minimum current density of 417.3 mA cm−2 is recommended to achieve at least parity with hydrogenation in terms of production cost. To push the commercialization of gas-phase electroreduction, besides current density improvement, electricity cost reduction, and carbon trading mechanism is proposed to reduce the production cost.

Mechanical properties and oxidation corrosion resistance of phosphate ceramic coating enhanced by SiO2‐BNNSs material

AbstractA method of preparing SiO2‐BNNSs hybrid material by surface modification of boron nitride nanosheets (BNNSs) with SiO2 was proposed to improve the dispersion of BNNSs in the coatings. Then, phosphate ceramic coatings with BNNSs and SiO2‐BNNSs were prepared on stainless steel (304) by spraying. Characterization of BNNSs and SiO2‐BNNSs by X‐ray diffraction, Fourier transform‐infrared, Raman, and scanning electron microscopy proved the success of hybridization. The surface morphology and mechanical properties were conducted to characterize the protective performance of the coating. Simultaneously, the phase composition and electrochemical properties of the coatings after high‐temperature oxidation were studied. The results showed that ceramic coatings had low surface energy with a contact angle of 102.41° when .4 wt.% SiO2‐BNNSs was added. Compared with BNNSs coating, the mechanical properties of SiO2‐BNNSs coating were significantly enhanced, the hardness of .4 wt.%SiO2‐BNNSs coating was as high as 170 HV, and the interface bonding strength was 12.24 MPa. For the oxidation corrosion resistance, .4 wt.% SiO2‐BNNSs coating under oxidation at 400°C for 50 h had the minimum corrosion current density and maximum impedance, which were .864 μA/cm2 and 177 kΩ/cm2, respectively, this indicated that SiO2‐BNNSs coating could still maintain excellent oxidation corrosion resistance under high‐temperature conditions for a long time.

Understanding the behaviour of magnetic field distribution of railgun under transient conditions using finite element method

The magnetic field distribution in the rails is a crucial factor in comprehending railgun behaviour. The projectile's rapid movement has a significant impact on the magnetic field. If the dispersion of the magnetic field conclusions regarding the conductors are known suitable methods can be used to sketch the magnetic field distribution. The railgun operates on the premise that a high current flow through the rails and armature will create a strong magnetic field. As a result, before designing magnetic shielding, it is necessary to study the features of the magnetic field distribution. The shape of rail and armature cross section is very essential in rail gun design as it determines the magnetic field distribution over rail and armature. The rail gun geometries with rectangular, convex and concave rail cross-sections are compared and simulated using finite element method (FEM). This method is used to determine the magnetic field distribution over rail and armature by sweeping armature position for different rail cross sections. It is observed that for the different rail/armature shapes like rectangular, convex and concave shapes, the C shaped convex armature possesses strong magnetic fields with minimum current density concentration at the throat and trailing end of the armature. From simulation, it can be shown that the magnetic flux density is a descending function of the central angle. The electromagnetic (EM) rail gun launching mechanism was therefore proven to be compatible with the circular concave armature.

Preparation and corrosion resistance mechanism of chromium-free Zn–Al+CeO2 composite coatings

This study aims to fabricate chromium-free Zn–Al + CeO2 composite coatings by integrating CeO2 nanoparticles into the chromium-free Zn–Al coating solution as a strengthening agent and subsequently applying a wet coating method. The corrosion resistance of the coatings was evaluated through NaCl immersion corrosion tests. The microscopic morphology, composition and electrochemical properties of the composite coatings before and after corrosion were analyzed using SEM and an electrochemical workstation. The corrosion resistance mechanism of the coatings was investigated as well. The results revealed that the CeO2 nanoparticles were uniformly distributed on the surface of the composite coating and in the gaps between Zn and Al powders, forming micron-sized particles due to the surface energy effect. The composite coating exhibited a minimum corrosion current density of 0.63 μA cm−2 and a maximum corrosion electrochemical reaction resistance of 35321 Ω cm2. Additionally, a complex precipitate formed by the reaction of certain Ce elements in the composite coating enhanced the cathodic protection of the coating. Moreover, Ce3+ reacted with the OH− generated by microelectrochemical corrosion, resulting in the formation of a precipitate that filled in the gaps between Zn and Al powders. Consequently, this process contributed to the formation of a microporous and flocculent coating structure. In conclusion, the incorporation of CeO2 nanoparticles had a favorable impact on the production of environmentally friendly and corrosion-resistant chromium-free Zn–Al coatings.

Microstructural Evolution and Magnetic and Corrosion Properties of FeCoNiAl0.2Yx High-Entropy Alloys

FeCoNiAl0.2Yx (x = 0, 0.05, 0.1, 0.2, 0.3) high-entropy alloys (HEAs) with different Y contents were prepared by a vacuum arc melting method, and experimental methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), vibration sample magnetometer (VSM), hardness tester, and electrochemical workstation were used. The effects of rare Earth Y content on the microstructure, magnetic properties, and electrochemical corrosion properties of the alloy were investigated. The results showed that all FeCoNiAl0.2Yx alloys had a dendrite structure. When x = 0, the alloy consists of the FCC phase, after adding Y element, the HCP2 phase appeared in the alloy, and when x = 0.3, only the HCP1 phase existed in the alloy. The hardness of the alloy increased with the increase of Y content. The FeCoNiAl0.2Y0.1 alloy had the best magnetic properties, reaching a maximum saturation magnetization strength (Ms) of 139.25 emu g−1. The hysteresis area of FeCoNiAl0.2Yx alloys was very small, basically zero, and the hysteresis curves showed a very small lag. The corrosion potential of FeCoNiAl0.2Y0.1 alloy was −1.010 V, and the minimum corrosion current density of FeCoNiAl0.2Y0.1 alloy was 1.181 × 10−5 A cm−2. FeCoNiAl0.2Y0.1 alloy had relatively high corrosion potential and minimum corrosion current density and had excellent corrosion resistance.

Improving Performance of Organic Photodetectors by Using TCNQ Doped Copper Thiocyanate as the Anode Interfacial Layer

AbstractThe responsivity and specific detectivity are critical figures of merits for organic photodetectors; however, it remains challenging to simultaneously enhance two such parameters, since enhancing external quantum efficiency corresponding to responsivities will inevitably increase leakage current and noises, resulting in decreased specific detectivity. To address such a trade‐off, an effective anode interfacial layer of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) doped copper thiocyanate (CuSCN) is developed herein, which can enhance shunt resistance, increase depletion width, enhance hole extraction efficiency, as well as reduce trap density of states of organic photodetectors. The organic photodetectors based on doped CuSCN present a very low dark current density of 4.4 × 10−11 A cm−2 and an impressively high specific detectivity of 1.1 × 1014 Jones. As evidenced by X‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy measurements, the energy levels of the doped CuSCN:TCNQ film are deepened, associated with the occurrence of dopant bonding and charge transfer. In addition, it is found that increasing the delay time can suppress the hysteresis effects of current density–voltage characteristics of organic photodetectors and make the minimum dark current density obtainable at 0 V. These findings demonstrate the great potential of using molecular doping to adjust the anode interfacial layer for developing high‐performance organic photodetectors.

Enhancement of microbial fuel cell performance by introducing dosing materials in waste water to increase microorganism growth

This study uses the microbial electrochemical process to produce energy from wastewater. The bacterial growth in sewage has been controlled by applying molasses, vegetables and waste coffee as dosing materials. High-conductive silver metal has been used as an anode, whereas graphite has been used as a cathode. An agar salt membrane has been used as a separator to ensure high hydrogen-ion exchange. During bacterial culture, it is revealed that 21,600,000 cfu/ml, 14,800,000 cfu/ml, and 38,700,000 cfu/ml number of bacteria is observed for molasses, vegetable protein and waste coffee, respectively. In each dosing, E.coli, S.aureus, and Salmonella sp. were identified. The bacterial growth highly influenced electrical energy production in this method. The wastage of coffee produced more energy and grew more bacteria. Waste coffee had a maximum current density of 809.40 mA/m2 and a maximum power density of 10622.496 mW/m2, respectively. In contrast, the minimum current and power density values, 166.15 mA/m2 and 408.726 mW/m2, were attained, respectively. The produced energy is much higher than the information available in the literature. The applied method can be used in various sectors to generate electrical energy.

Effect of Sn on corrosion resistance of Ti-Cu-Ni amorphous coating

Ti50Cu35-XNi15SnX (X = 5,6,7, wt%) Ti-based amorphous composite coatings were prepared on TA1 by atmospheric plasma spraying. The phase and microstructure were analysed by X-ray diffractometerand scanning electron microscope. The obtained cross-section image of the titanium-based amorphous composite coating confirmed the successful preparation of the amorphous coating. The phase analysis results indicated that an increase in Sn content resulted in a decrease in the amorphous content of the coating. The electrochemical results revealed a significant improvement in the corrosion resistance of the coating compared to the TA1 substrate, consequently enhancing the service life of the electronic material. When the Sn content was 5 wt%, the minimum current density of the coating reached 8.62 × 10-6 A/cm2, and the corrosion rate was 16 times lower than that of the TA1 substrate. As the Sn content increased, the current density of the coating increased from 8.62 × 10-6 A/cm2 to 5.08 × 10-5 A/cm2. Overall, the corrosion resistance of the coating exhibited a downward trend. This observation could be attributed to the decrease in amorphous content caused by the higher Sn content, resulting in a reduction in the corrosion resistance of the coating.

In Situ Growth of High-Performance ZnAl-Layered Double Hydroxides/Al2O3 Composite Coatings on Aluminum Alloy

In this research, high-performance ZnAl-layered double hydroxides (ZnAl-LDHs) with different Zn2+ concentrations were prepared on the surface of an anodized 1060 aluminum alloy using the in situ growth method, and the influence of Zn2+ concentration on corrosion resistance and tribological behavior was further explored. The surface morphology, element distribution, phase composition, and mechanical performance of ZnAl-LDHs/anodic aluminum oxide (AAO) composite coatings were tested and analyzed. Subsequently, the investigation of the anti-corrosion properties and tribological behavior of as-prepared composite coatings and AAO were conducted experimentally. The results show that with the increase in Zn2+ concentration, the thickness and bonding strength of the coatings gradually increase, and the hardness progressively decreases. The ZnAl-LDHs/AAO composite coating with a Zn2+ concentration of 0.3 mol/L exhibits the best anti-corrosion ability, which has the minimum corrosion current density of 2.435 × 10−9 A/cm2. This can be attributed to the uniform and compact ZnAl-LDH films where the porous structure of the AAO is well sealed. Moreover, the excellent friction-reduction and anti-wear properties of ZnAl-LDHs/AAO composite coatings with larger Zn2+ concentrations are verified using a ball-on-disc rotating wear tester under dry wear. A reasonable mechanism for improving tribological properties of resulting ZnAl-LDHs/AAO composite coatings is proposed.

The impacts of membrane pinholes on PEM water electrolysis

Polymer electrolyte membrane (PEM) water electrolysis is a promising technology to efficiently produce green hydrogen. Irregularities in membrane electrode assembly (MEA) component materials caused by manufacturing, processing, handling, or operation can lead to performance loss and failure. One example is the presence of pinholes in the membrane, which can cause increased gas transport (crossover) and lead to electrical shorting. This work investigates the effects of intentionally introduced pinholes with various sizes up to 350 μm in diameter. The presence of the pinholes resulted in minimal impacts on the cell voltage (±30 mV at 4 A cm−2). However, the pinholes significantly increased H2 crossover, which decreased hydrogen production efficiency and increased the minimum current density for safe operation. The impacts of the pinhole on the H2 crossover and efficiency are more severe for open pinhole features than tear-like pinhole features. This research demonstrates that even small pinholes cannot be disregarded from a safety, efficiency, and operating strategy perspective.

Effect of Rough‐Surfaced Diamond Content on the Microstructure, Tribological Behavior, and Corrosion Resistance of Ni/Diamond Composite Coatings

This study fabricates certain Ni/diamond composite coatings using a coelectrodeposition method and then evaluates the effect of diamond content on the morphology, phase structure, microhardness, wear, and corrosion resistance of such coatings, while exploring their tribological and anticorrosion mechanisms. It is demonstrated that the addition of diamond can change the preferred orientation of Ni from (200) to (111), and its texture coefficient value can be boosted from 23.3% to 64.4% with the increase of diamond content. In the experiment, at a diamond content of 3 g L−1, the deposited diamond particles are more and evenly dispersed across the composite, with the microhardness of nickel‐based coatings reaching an optimum value of 613 HV. In addition, the coefficient of friction is reduced to a minimum value of 0.627, while the wear rate is kept at only 1.79 × 10−5 mm3 Nm−1, indicating a high wear resistance. Electrochemical test results demonstrate that the Ni/diamond composite coatings produced at 3 g L−1 create the maximum charge transfer resistance (5429.3 Ω cm2) and the minimum corrosion current density (2.19 μA cm−2), features that can deliver the best corrosion resistance.